> Boeing found that adding several more feet to the 777's wingspan had the
> same effect of adding winglets, and that stretching the wing did not require
> the reinforcement necessary for winglets. In otherwords: stretching the wing
> was more structurally efficient.
Not true. For the same span extension (measured with the winglet laid down flat), winglets produce the same drag reduction or slightly more than wing tip extensions. Wing tip extensions also produce more bending moment than winglets. Hence, the wingtip extension would require more structural reinforcement than required for winglets.
The problem with the 777 wing is that Boeing designed it with relatively high lift coefficients near the tip. They figured that if the wing wasn't carrying much lift there, they would minimize the chord, which drives up the lift coefficients. This makes it difficult to put a winglet on this wing.
> Next, the winglet is hardly the epitome of aerodynamics.
> The 787 features a new generation of winglets known as "super-shark
> winglets." FD
tried something simmilar before going belly-up.
The design concepts that have been released and public comments show the 787-3 to have winglets and the 787-8 and 787-9 to have non-planar raked tips.